There is an increased demand for heavy aromatic solvents containing a substantial amount of alkylnaphthalenes. Such solvents are typically used for such things as reclaiming rubber, as cleaning agents, as carriers for oil field chemicals, as carriers for industrial chemicals, and in pesticides. Non-limiting examples of such solvents are those designated as aromatic 100 solvent (A-100), aromatic 150 solvent (A-150), and aromatic 200 solvent (A-200). A-200, which generally contains from about 75 to 95 wt. % alkylnaphthalenes, is in particularly high demand. The market for such solvents is very lucrative because demand for such heavy solvents currently exceeds production. These aromatic solvents are conventionally produced by various techniques.
One such technique is found in British Patent No. 977,642 to British Petroleum which teaches a process for producing aromatic solvents by fractionating a reformate cut boiling in the range of 145.degree. C. to 200.degree. C., then treating this cut with sulfuric acid. Also, U.S. Pat. No. 3,398,083 discloses the production of aromatic hydrocarbons by solvent extraction. The resultant aromatics can then be fractionated into benzene, toluene, individual C.sub.8 isomer streams, and a C.sub.9 +aromatics stream. Further, U.S. Pat. No. 3,324,029 teaches a process for producing a heavy aromatic solvent by steam cracking a gas oil to produce a heavy tar, which is then heat soaked and flashed and a 175.degree. C. to 290.degree. C. boiling fraction is recovered.
While one of the most commonly used methods today for producing heavy aromatic solvents is the distillation of reformer bottoms, most refineries do not have distillation facilities associated with reformer units. While additional distillation facilities can be built to produce such solvents from reformer bottoms, the capital investment would be substantial.
Therefore, there exits a need in the art for methods of increasing the production of these heavy aromatic solvents in existing equipment without the need for substantial capital investment.